The present invention relates to the field of ligand/receptor interaction evaluation. More specifically, in one embodiment the invention provides a novel system for the determination of the binding affinity of a receptor to a surface-bound, high-density ligand array and vice versa (ligand to bound receptor). Due to the nature of the immobilized array, this system also permits measurements of both on- and off-rates of receptor binding. In a particular embodiment, the present invention provides a method and device for quantitation of binding affinity utilizing fluorescence intensity data from labelled receptors bound to peptides which have been synthesized or immobilized on a solid support. In another embodiment, the present invention provides a method for determining the fidelity of synthesis of peptides by comparing the fluorescence intensity of a receptor bound to an array to the fluorescence intensity of the receptor bound to an array of known purity and composition.
Techniques have recently been introduced for synthesizing large arrays of different peptides and other polymers on solid surfaces. For example, in Pirrung et al., PCT Publication No. WO 90/15070, incorporated herein by reference for all purposes, a technique is disclosed for generating arrays of peptides and other materials using, for example, light-directed, spatially-addressable synthesis techniques. See also U.S. patent application Ser. No. 07/624,120 (Fodor et al.) which discloses, among other things, a method of gathering fluorescence intensity data, various photoprotective groups, masking techniques, and automated techniques for performing light-directed, spatially-addressable synthesis techniques. Because of their relationship to semiconductor fabrication techniques, these methods have come to be referred to as "Very Large Scale Immobilized Polymer Synthesis," "VLSIPS.TM." synthesis technique. Such techniques have met with substantial success in, for example, screening various ligands such as peptides to determine their relative binding affinity to a receptor such as an antibody.
While meeting with substantial success, such techniques generally provide a qualitative estimate of binding affinity for a ligand-receptor pair as well as the relative order of affinities for a multi-ligand substrate. Other techniques of measuring binding affinity provide only indirect indications of binding affinity.
It is desirable to provide a direct method and device for more precisely determining the binding affinity of a receptor to a specific ligand substrate synthesized in a multi-ligand array.